Exemplary embodiments of the present disclosure relate to a heat transfer tube having a rare-earth oxide superhydrophobic surface and a method for manufacturing the same, and more particularly, to a heat transfer tube having a rare-earth oxide superhydrophobic surface by depositing a rare-earth oxide layer and a method for manufacturing the same.
A nuclear power plant or a thermal power plant generates heat using uranium, petroleum, coal, or the like as fuel to heat a water circulating a system with the generated heat, thereby forming steam. The formed steam rotates a turbine to produce electricity and the steam passing through the turbine is cooled in a condenser to be changed to water again. In particular, in a steam circulation power generation system, a water cooling type that performs cooling with water in a condensing process requires a large quantity of cooling water. Here, as the cooling water used in the condenser, sea water is used. Therefore, to smoothly supply and discharge the sea water used as the cooling water, the steam circulation power generation system is generally installed near the coast.
In other words, the condenser is expressed as a steam condenser and the steam condenser makes sea water continuously flow in a heat transfer tube of the condenser to continuously turn a temperature of an inner wall of the condenser down. Then, the steam is cooled in the moment that steam discharged through a valve to rotate the turbine is directly bumped into the inner wall of the condenser and becomes condensed water (in a state in which steam returns to water) and the condensed water again returns to a boiler pipe into water of about 500° C. and passes through the turbine via the valve.
The boiler continuously makes hot water into supersaturated steam and belches out the steam to the turbine through the valve and the steam condenser continuously repeats a process of suddenly cooling the steam to return the steam to water again.
At this point, the cooling water cooling an outer wall of the condenser requires a large quantity of water incomparable to that of the cooling water cooling the mechanical friction heat, and sea water needs to be continuously supplied while a power generator is operated.
The steam rotating the turbine contacts the inner wall of the condenser, and thus is cooled into water. At this point, to increase the quantity of steam contacting the inner wall of the condenser, a plurality of heat transfer tubes are included to increase a contact area.
The condenser may corrode due to condensation at an outside of the tube, and may corrode due to a condensed fluid remaining on a surface thereof, and the like. Similarly, even in the case of a heat exchanger used in a power plant, the condenser may corrode due to the condensation at the outside of the tube when heat is exchanged between channels crossly passing through a heat transfer plate, and corrode due to the condensed fluid remaining on the surface thereof, and the like.
One attempt to address this problem is a cross-linked repellent thin film that includes resin having a fluorine atom containing group; quaternary ammonium group-containing modified epoxy resin; and amino resin. However, the repellent thin film has a problem in that it is difficult to form a superhydrophobic thin film in which a contact angle between the surface thereof and a water drop is equal to or more than 150° and it is difficult to hold repellent coating even under a high temperature environment.
Therefore, an improved heat transfer tube and a method for manufacturing the same capable of forming superhydrophobic thin film and of holding repellent coating even under the high temperature environment is desirable.